Distinguish layer references

Distinguish references to db and service level namespaces (aka rename), e.g. not using **:as workflow** for both `rems.db.workflow` and `rems.api.services.workflow`

Consider also whether something is singular or plural.

Do after #2783

Start by reviewing the outcome of #2783 and locate the references to rems.db.workflow and rems.api.services.workflow. Determine the intended rename and whether each namespace should be singular or plural; the work is done when these layer references are distinguishable without relying on the shared :as workflow alias.

Written by the indexing model from the issue text.